Heat exchange apparatus



Jam 2%,, 193%. PRESTAGE zfiz flfi HEAT EXCHANGE APPARATUS Filed Aug. 28, 1935 3 Sheets-Sheet l ATTORNEY Jam, 2%, 11%36. PRESTAGE ED295033 HEAT EXCHANGE APPARATUS Filed Aug. 28, 1935 3 Sheets-Sheet 2 3 4 f 4 a w w f; f/AVE/W'O/P A TTOENEY:

E. PRESTAGE ZGZQEQB HEIA' I EXCHANGE APPARATUS Filed Aug. 28, 1935 3 Sheets-Sheet 3 3 Wmvme ATTORNEY Patented Jan. 28, 1936 UNITED STATES PATENT OFFICE Application August 28, 1935, Serial No. 38,249 in Great Britain May 25, 1934 1 Claim.

which channels or passages for the liquids are constituted by metal plates provided with facial ribs or the like, which are adapted to furnish zigzag courses for the liquids when a series of such plates are clamped together.

When heat exchange apparatus of this type is used for pasteurizing milk and like processes, it is essential that the channel through which the milk passes should be cleaned at regular intervals. This is done by taking apart the plates so that the surfaces which make up these channels may be thoroughly cleaned. In existing types of apparatus it has been necessary to open up not only the channels through which the milk flows but also the channels through which the heating or cooling medium, usually brine or water, flows. In consequence considerable inconvenience may be caused by unnecessary opening of these brine or water channels on account of the escape of these liquids onto the floor.

In order to overcome these difliculties, apparatus with hollow plate elements have been designed in which the heating or cooling medium is retained within the plates when the apparatus is opened for cleaning, but in these cases the plates have been cast in a single piece, with the results that the interchange of heat is inferior and also that manufacturing costs are high owing to the difiiculty of obtaining sound castings.

The object of the present invention is to provide plate heat exchange apparatus of the type described which may be easily cleaned without the necessity of disturbing the channels through which the heating or cooling medium flows, and which is constructed with the usual thin metal sheets as heat interchange walls between adjacent channels through which the liquids flow.

Briefly stated the present invention comprises apparatus of this type in which the plates are hollow and comprised of narrow metal frames provided with metal closure sheets and bafiie strips extending across the frames between the sheets and adapted to form a zig-zag channel for the passage of the heating or cooling medium within the interiors of said frames and in which the exterior surfaces of the sheets which form the heat exchange walls of said frames are provided with metal strips in register with the bafile strips within their frames adapted to form channels between adjacent plates for the passage of the liquid under the heat exchange treatment.

My invention is shown by way of example in the accompanying drawings in which:

Figure 1 shows a side view of a heating and cooling unit,

Figure 2 shows a plan view of Figure 1,

Figure 3 shows a side view of a heat exchange plate according to the present invention,

Figure 4 shows a transverse section on the line IV-IV of Figure 3 through a pair of contacting plates,

Figure 5 shows a vertical section on the line V-V of Fig. 4 of the plate shown in Figure 3, and

Figure 6 shows a detail view on an enlarged scale of a rivet connecting the side sheets.

In the embodiment of the invention shown in the drawings, flat sheets I of metal which form the side walls of a hollow plate unit, are brazed, soldered or welded to each side of a narrow metal frame or casting 2. Any other means of attaching said sheets to the frame in such a manner as to make a fluid-tight joint may be employed. Between the sheets I and fixed across the metal frame are spaced bafiie strips 3. These strips form with said side walls I a zig-zag channel for the passage of the heating or cooling medium within the interior of the plate. The exterior surfaces of said sheets I which form the side walls of this unit which are exposed to the liquid to be heated or cooled, form plain fiat surfaces which are broken only by thin metal strips 4 placed exactly over and in line with the frame strips 3 forming the bafiles Within the plate.

It will be undertood that when two of these plates are placed together the strips 4 of each pair of adjacent plates are in contact with each other and form zig-zag channels through which the liquid under the heat exchange treatment is forced to flow in a corresponding path to the path of the heating or cooling medium within the interiors of the plates. The flow of the liquid under treatment is usually in a counter direction to the flow of the heating or cooling medium.

This plate construction is particularly suitable when it is desired to use stainless steel sheets for the surfaces in contact with the liquid under treatment.

In order to assemble the series of component parts into a plate, a series or" pins 5 are passed through holes drilled through the metal strips 4 which are in line with each other as shown in Figure 6. These pins 5 may be fixed either by countersunk riveting or by soldering as shown. Alternatively the pins may be screwed.

The cooling or heating medium enters and passes out of the plates through the pipes 6 let into the frames between the sheets I, and the liquid under treatment enters through holes 1 r to the casting around these holes l.

formed at the corners of both the sheets and the main frame castings. These holes 1 are in line when the plates are assembled to form a heating unit so that the liquid under treatment enters simultaneously under pressure the spaces between the adjacent plates. The sheets I are attached by rivets or screws as described above After the heating or cooling treatment the liquid passes out of the apparatus through similar registering holes formed in the sheets and frames at another comer.

' The plates when assembled are held together by two cover plates l2 one at each side of the unit; these cover plates are held together by a series of bolts I3 passing through registering holes in the cover plates and secured by nuts M. 7

To prevent leakage of the liquid under treatment between the plates a metal to metal joint is mainly depended upon around the inner edges of the peripheral joint between the plates, but also outside this metal joint a rubber joint is provided let into the groove 9 such as is in common use for a similar purpose in beer filters, milk separators, coolers and the like. It is undesirable for the liquid under treatment to come into contact with rubber owing to the possibility of bacterial contamination, therefore a groove iii is provided between the metal to metal joint on the inner edge of the frame nearest to the liquid and the groove 9 containing the rubber joint. The liquid under treatment will only leak in the event of the inner metal to metal joint becoming damaged. In this event the groove to presents an annulus into which this leaking liquid may pass. The rubber joint will prevent this liquid from leaking outside the apparatus, while any liquid finding its way into the groove 9 and coming into contact with the probably contaminated rubber joint cannot pass back into the main stream or body of liquid under treatment on account of the lower pressure existing in the groove. When the apparatus is opened for cleaning this small amount of contaminated liquid will fall away.

For the purpose of cleaning the inside surfaces of the plates I provide at each end of each channel a removable plug ll so that a stifi scraper, wire brush or the like can be passed through from either end and the inside easily cleaned when necessary.

What I claim is:-

A heating unit for the interchange of heat between two streams of fluids, such as milk and steam, comprising a plurality of identical plates,

each plate having a narrow metal frame mounted between two relatively thin metal closure sheets,

said sheets forming the heat-exchange surfaces of the plate, bafile strips extending across the interior of the frame between said closure sheets and forming a zig-zag channel for the passage of the steam, metal strips on the exterior surfaces of both closure sheets, the metal strips being half. 

